1. Field of the Invention
The present invention relates to a non-crystalline polyester resin composition. More particularly, the present invention relates to a non-crystalline polyester resin composition which comprises a non-crystalline polyester resin component and an epoxy-modified block copolymer component obtained by epoxidation of unsaturated bonds in a block copolymer comprising a block polymer of a vinyl aromatic compound and a block polymer of a conjugated diene compound, the resin composition being in a specified range with respect to an epoxy-equivalent, an absolute difference value between the refractive index of each component and a mixed ratio of each component, being excellent in moldability and secondary processing properties, being improved in transparency and impact-resistance of a molding thereof and being given a balanced mechanical strength.
2. Description of the Related Arts
A non-crystalline polyester resin is excellent in processing properties of its molding, mechanical properties and chemical properties, in addition to its moldability, and is used in a variety of fields.
In more detail, the non-crystalline polyester resin is excellent in such moldability as extrusion-, injection-, hollow-, rotational-, compression-, pressure-, vacuum- and free blow-molding, and besides excellent in such mechanical processing as cutting, grinding and bending processing of a film, sheet, plate, container or the like obtained by its molding, in such adhesive processing properties as ultrasonic adhesion, heat adhesion and solvent adhesion, and in such secondary processing properties as silk printing, gravure printing and pad printing. Moreover, the above-mentioned polyester resin and the moldings thereof are excellent in a solvent resistance and an oil resistance, and accordingly are widely used for automobile parts, electronic machinery and tools, office-work appliances, or packages of medical appliance parts, various protective covers, display sheets, indoor partitions, floor materials such as a flooring, refrigerators, containers for frozen food, containers for miscellaneous goods, or the like.
Although the non-crystalline polyester resin has a weak point in transparency and impact strength of a molding thereof, recently, the non-crystalline polyester resin or its molding having an appropriate softness as well as an excellent transparency and a high impact resistance, specifically in the fields of the display sheets, indoor partitions, package films, containers, or protective covers, among the above-mentioned various fields for use, has been sought up to the present.
In general, an elastomer having a rubber-elasticity or a compatibility-enhancing agent is added, as means to solve the impact resistance and also the softness-improvement of a synthesized resin, its resin composition or a molding thereof. In almost cases as such, the molding decreases visual transparency thereof and it is impossible to satisfy impact resistance or softness with transparency at the same time. Accordingly, the above-elastomer or the compatibility-enhancing agent has not been utilized appreciably for the objects which require transparency.
In order to improve the visual transparency, it is well known that the compatibility-improvement of the resin component to be mixed with the elastomer or the like and moreover allowing each refractive index of the components to come as near as possible are effective. However, it has been, heretofore, considered impossible to find out a resin composition which has a high visual transparency in a solid phase and gives impact resistance and softness effectively.